Yet another coolant leak thread

[ryushe]

After having experienced a cracked expansion tank late last year which was replaced (along with the hoses), I'm now suddenly facing another coolant leak. Drove the car home yesterday, a roughly 100km trip, and parked it. No issues at all during the trip, or the days prior.
Today however, the moment I started the car I got a yellow coolant light in the dash. Checked the level, and it was WAY low, however the ground was dry. Now it's 28 degrees here, so it might have evaporated overnight, but I suspect coolant fluid would leave some residue at least. Anyways, I topped up the coolant and went off on some errands I needed to do.
After driving around 15km, coolant light comes on again. Pulled over, waited a bit, and checked level again. And you guessed it, it's way too low. Now this time there's some liquid visible on the undertray and dripping out the little hole in the center of the tray, but no clear indication where it came from. I know how much fluid I added, and given the short trip, I'd expect a clear trail or at least something literally spouting fluid, but no.
Checked the expansion tank, hoses and clamps, and everything seems fine. Exhaust is clear, no smoke, so at this time I don't suspect a headgasket failure.

Car is a 2006 3.0si with N52 engine.

Any tips on where to look, or what to diagnose? It's a daily driver, and is supposed to go on a 4000km trip in a few weeks, which has me a bit worried...

[bigwinn]

When it’s up to temp it can come out in a fine spray or mist…

I’d get the front up, undertray off and run it, you’ll see where it’s coming from by shining a torch

[ryushe]

So had a look underneath, can't see a thing
Coolant level was low again, so filled it back up and went for a test drive. The yellow low coolant level light came on after around 15/20km again, but before that happened I noticed my temp gauge crept up towards the red three times before settling down at dead center again (I've never seen it above dead center before). This seems to indicate the fan certainly seems to work.

With that said, and from reading around a bit, could this be the preliminaries of a failing water pump? Could that lead to coolant loss?
Cause if it is I'm ordering a Pierburg one right now, along with a new thermostat while I'm at it. If I'm going to tackle this anyways, would you guys suggest I replace the hoses at the same time, and also, which ones would you suggest? The ones for the tank and radiator (parts 1, 2, 4 in diagram) or the ones on the engine side (parts 1, 7 in diagram)?

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[ryushe]

Update for future visitors; in my case (as described above) it turned out to be a failed waterpump. It failed to the point of no longer actually pumping at all. Either it's unrelated, or this somehow also caused the upper radiator hose to develop an invisible leak, which I only found after getting a shop to do a pressure test.
Replaced the pump, hose, and thermostat while I was at it, and everything is now back to normal.

[MeinMotorradsZ4]

Related to your issue - Sometime in the 90s my parents Vauxhall Cavalier started losing coolant, temps rose etc but no water on the ground; fault was traced to a pin hole in the back of the radiator that only opened up to leak when the engine was up to temp.